#include <Ultrasonic.h>
Ultrasonic ultrasonic(13,12);
int BUZZER = 2;

void setup() {
  pinMode(BUZZER,OUTPUT);
}

void loop() {

  int distance = ultrasonic.read(CM);

  tone(BUZZER, 1000);
  delay(100);

  if(distance<100){
    noTone(BUZZER);
    delay(100);
  }else if(distance >= 100 && distance <=300){
    noTone(BUZZER);
    delay(500);
  }else if(distance>300){
    noTone(BUZZER);
    delay(1000);
  }
}